Valves and valve systems are used to control pressure within containers and flow into and out of containers. Further, valves can be used to prevent overpressure situations from occurring. For example, a container may be overfilled such that fluid may potentially rupture the container. Similarly, a tank may be filled to an appropriate level, but as the temperature rises, the pressure within the tank may also rise, thereby causing an overpressure situation. In this manner, an overpressure valve may be used to slowly release fluid and prevent the container from rupturing. Additionally, rupture discs may also be included in such a valve system to prevent fluid from contacting the pressure relief valve until an overpressure condition exists.
Such valves and valve systems can be utilized in a number of applications. For example, these valve systems are often used in rail cars for transporting fluids, including liquids and/or gas. Generally, rail cars include at least one location on the car where inlet and outlet valves may be located, along with other related devices, such as pressure control valves, gauges and other structures. However, generally these valves, including pressure relief valves, are often located on an exterior of the rail car. By having the valves located on the exterior of the rail car, the valves are more prone to being damaged and/or accidentally removed if contacted by other machinery or if the rail car were to overturn.
Valves, including overpressure valves, are also used on other containers such as ISO and tote tanks. In general, an ISO tank is a pressure vessels mounted in a frame that complies with the standards of the International Standards Organization (ISO). ISO and tote tanks are commonly used for transporting chemicals, especially internationally. In some instances, these types of tanks are approximately one quarter the size of rail cars. Additionally, the tanks are built with frames or other structural support surrounding the tank to protect the tank and allow it to sit squarely on the ground or on top of other tanks. These types of tanks can be transported in a number of ways, including, but not limited to, rail, truck and sea.
ISO and tote tanks generally include similar valves and valve systems to those described with respect to rail cars. For example, ISO and tote tanks may include overpressure valves and/or rupture discs for preventing the tanks from rupturing during an overpressure situation. Just as described with respect to rail cars, ISO and tote tanks are also susceptible to tipping over and/or having the valves damaged or broken off by other machinery.
Furthermore, typical pressure relief valves and rupture discs are often interconnected such that if one component requires servicing or replacement, the entire system must be removed. This can be problematic, especially if the tank contains fluid that must be drained prior to removal or servicing of the system.